Reflection and scattering of spin waves by surface roughness of a ferromagnet

Abstract

A detailed theory of volume spin wave reflection from the randomly rough surface of a ferromagnet is presented. The contribution to damping of the reflected wave is calculated. This contribution is due to the scattering of the initial volume wave into secondary surface and volume spin waves. The value of damping is proportional to the correlation length and the square of the roughness amplitude. Numerical calculations of the attenuation rate as a function of the angle of incidence and the ratio between the surface anisotropy and the wavenumber are provided. They yield the angle of incidence where the attenuation has a maximum. In analogy to optics, this angle is similar to the Brewster angle. Numerical estimations of damping and a comparison of its value with the ferromagnetic resonance linewidth are also made. Finally, the results of the calculation of the scattering of surface exchange spin waves by surface roughness are presented and discussed.